Liquid repellent cloth, liquid repellent film, umbrella, and product

ABSTRACT

A liquid repellent cloth or liquid repellent film according to an embodiment includes abase fabric selected from a fiber cloth or a synthetic resin film, and a liquid repellent membrane supported on at least one principal face of the base fabric. The liquid repellent membrane is a monomolecular membrane of a fluorine-containing organic compound that binds to a surface of the base fabric through a binding moiety represented by —Z—O—* (wherein Z represents an atomic group containing a Si atom, and * represents a binding site to the surface of the base fabric) and includes a perfluoroalkyl group having 4 or less carbon atoms at a terminal, and the fluorine-containing organic compound undergoes intermolecular bonding between the fluorine-containing organic compounds adjacent to each other by mutual binding of Z in the formula.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2020-051726, filed on Mar. 23, 2020 the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a liquid repellent cloth, a liquid repellent film, an umbrella, and a product.

BACKGROUND

As one antifouling technique for a product, liquid repellency (water and oil repellency) is generally imparted by forming a fluorine-based liquid repellent membrane on the surface. An explanation is provided by showing an umbrella as an example. As a canopy of a fabric umbrella, a woven fabric of a synthetic fiber such as a polyester fiber or a nylon fiber is generally used, and as a canopy of a so-called plastic umbrella, a synthetic resin film is used. The surface of such a canopy is coated with a fluorine-based liquid repellent membrane for imparting liquid repellency. The liquid repellent membrane is likely to be abraded, for example, when an umbrella is closed and folded or due to rain, wind, or the like. When the liquid repellent membrane is abraded, the liquid repellency is deteriorated, and the liquid repellent membrane no longer repels water or oil in the end. Therefore, the liquid repellent membrane is required to have not only excellent liquid repellency, but also excellent abrasion resistance.

As the fluorine-based liquid repellent membrane, a silane-based compound having a long-chain perfluoroalkyl group is often used. However, when the number of carbon atoms of the perfluoroalkyl group is 5 or more, the compound is not degraded in nature, and therefore, there is a problem of environmental load. Further, there is a concern that a degradation product of a silane-based compound having a long-chain perfluoroalkyl group is highly accumulated in a living organism, and therefore, there is also a problem that the working environment is poor.

On the other hand, when the number of carbon atoms of the long-chain perfluoroalkyl group was set to 4 or less, there was a problem that the liquid repellency decreases, and also the abrasion resistance deteriorates, and the liquid repellent membrane is easily peeled off when being used for a long time.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing an example of a cross section of a liquid repellent cloth or liquid repellent film according to an embodiment.

FIG. 2 is a schematic view showing a partial cross section of an umbrella including a liquid repellent cloth or liquid repellent film according to an embodiment as a canopy.

FIG. 3 is a schematic view showing an example of a liquid repellent membrane.

FIG. 4 is a schematic view showing another example of a liquid repellent membrane.

FIG. 5 is a schematic view showing another example of a liquid repellent membrane.

DETAILED DESCRIPTION

An object to be achieved by embodiments is to provide a liquid repellent cloth, a liquid repellent film, an umbrella, and a product having few problems of environmental load and working environment and having excellent liquid repellency and abrasion resistance.

According to an embodiment, a liquid repellent cloth or liquid repellent film including a base fabric selected from a fiber cloth or a synthetic resin film, and a liquid repellent membrane supported on at least one principal face of the base fabric, wherein the liquid repellent membrane is a monomolecular membrane of a fluorine-containing organic compound that binds to a surface of the base fabric through a binding moiety represented by —Z—O—* (wherein Z represents an atomic group containing a Si atom, and * represents a binding site to the surface of the base fabric) and includes a perfluoroalkyl group having 4 or less carbon atoms at a terminal, and the fluorine-containing organic compound undergoes intermolecular bonding between the fluorine-containing organic compounds adjacent to each other by mutual binding of Z in the formula is provided.

Further, according to another embodiment, an umbrella including the liquid repellent cloth or liquid repellent film is provided.

Further, according to another embodiment, a product including the liquid repellent cloth or liquid repellent film is provided.

Hereinafter, an embodiment is described in detail with reference to the drawings.

First Embodiment

FIG. 1 shows a schematic view of a cross section of a liquid repellent cloth or liquid repellent film according to an embodiment.

A liquid repellent cloth or liquid repellent film 1 shown in FIG. 1 includes a base fabric 20 and a liquid repellent membrane 30 supported on the base fabric 20. Hereinafter, the base fabric 20 and the liquid repellent membrane 30 is described in detail.

(Base Fabric)

The base fabric 20 is a base material selected from a fiber cloth or a synthetic resin film. When the base fabric 20 is a fiber cloth, the liquid repellent cloth or liquid repellent film 1 is a liquid repellent cloth, and when the base fabric 20 is a synthetic resin film, the liquid repellent cloth or liquid repellent film 1 is a liquid repellent film.

(Fiber Cloth)

The fiber cloth is a cloth containing a fiber. The fiber is not particularly limited, and may be any fiber of, for example, a synthetic fiber, a semi-synthetic fiber, a regenerated fiber, and a natural fiber. Examples of the synthetic fiber include polyester, polyamide such as nylon, an acrylic resin, and polyurethane. Examples of the semi-synthetic fiber include a diacetate fiber and a triacetate fiber. Examples of the regenerated fiber include rayon. Examples of the natural fiber include cotton, wool, hemp, and silk.

The polyester may be regular polyester obtained from terephthalic acid and ethylene glycol, or polytrimethylene terephthalate, polylactic acid, cationic dyeable polyester, or the like.

The fiber cloth may contain a yarn obtained by combining or mixed spinning such fibers, or may contain an interwoven product or an interknit product of a yarn composed of such a fiber.

The form of the fiber cloth is not particularly limited, and for example, a woven fabric, a non-woven fabric, and the like are exemplified.

(Synthetic Resin Film)

The synthetic resin film is not particularly limited, and for example, a polyester-based film, a polyamide-based film, and a polyolefin-based film such as a polypropylene-based film and a polyethylene-based film are exemplified. Further, the synthetic resin film may be a film of a copolymer thereof. In addition, as a material of the synthetic resin film, an ethylene-vinyl alcohol copolymer resin (EVOH), an ethylene-vinyl acetate copolymer resin (EVA), and the like are also exemplified. The thickness of the synthetic resin film as the base fabric may be, for example, between 50 μm and 200 μm.

<Liquid Repellent Membrane>

The liquid repellent membrane 30 is a membrane having liquid repellency. Here, the “liquid repellency” is a concept including both water repellency and oil repellency. Specifically, the “liquid repellency” refers to a property of repelling a liquid with respect to an aqueous or oily material in a liquid form, a semi-solid form, a gel form, or the like.

The liquid repellent membrane 30 is a monomolecular membrane of a fluorine-containing organic compound. The structure of the liquid repellent membrane 30 is described below with reference to FIGS. 3 to 5.

FIGS. 3 to 5 are each a schematic view showing an example of the liquid repellent membrane.

As described above, the liquid repellent membrane 30 is a monomolecular membrane of a fluorine-containing organic compound. The fluorine-containing organic compound (hereinafter also referred to as “fluorine compound”) includes a binding moiety 312 to the surface of the base fabric 20, a spacer linking group 32, and a perfluoroalkyl group 33. The fluorine compound is a molecule that includes the binding moiety 312 at one terminal and the perfluoroalkyl group (terminal perfluoroalkyl group) 33 at the other terminal, and includes the spacer linking group 32 therebetween, and the terminal perfluoroalkyl group 33 is present in a surface layer of the liquid repellent membrane 30. The fluorine compound may be linear or branched, but is preferably linear in order to increase the binding density to the base fabric 20 and improve the liquid repellency and abrasion resistance.

The binding moiety 312 is, for example, a moiety bound to the base fabric 20 by a reaction with a functional group present on the surface of the base fabric 20. Hereinbelow, the binding moiety 312 is sometimes represented by —Z—O—*. Here, Z represents a moiety denoted by the reference numeral 311 in FIGS. 3 to 5, and * represents a binding site to the surface of the base fabric 20. The details is described later.

The fluorine compound as a raw material of the liquid repellent membrane 30 includes, for example, a reactive functional group in a moiety corresponding to the binding moiety 312. In that case, by reacting the reactive functional group with the functional group present on the surface of the base fabric 20, the binding moiety 312 binds to the base fabric 20. The reactive functional group is, for example, a hydroxy group, an epoxy group, an amino group, or an alkoxy group, or an unsaturated hydrocarbon group such as a methacrylic group or a vinyl group, or a mercapto group. The functional group present on the surface of the base fabric 20 is, for example, a hydroxy group, a carboxy group, an amino group, or a thiol group.

Alternatively, the fluorine compound as the raw material of the liquid repellent membrane 30 includes an alkoxysilyl group in a moiety corresponding to the binding moiety 312. In that case, by reacting a silanol group generated by hydrolysis of the alkoxysilyl group with the functional group such as a hydroxy group present on the surface of the base fabric 20, the binding moiety 312 can bind to the base fabric 20.

Alternatively, the fluorine compound as the raw material of the liquid repellent membrane 30 includes an alkoxysilyl group and another reactive functional group in a moiety corresponding to the binding moiety 312. Here, the another reactive functional group is, for example, a hydroxy group, an epoxy group, an amino group, or an alkoxy group, or an unsaturated hydrocarbon group such as a methacrylic group or a vinyl group, or a mercapto group. In that case, for example, by reacting the another reactive functional group with the functional group present on the surface of the base fabric 20, the binding moiety 312 can be bound to the base fabric 20. Further, by subjecting a silanol group generated by hydrolysis of the alkoxysilyl group to dehydration condensation, an intermolecular bond can be formed between the fluorine compounds.

Hereinafter, the fluorine compound as the raw material and the fluorine compound forming the monomolecular membrane in the liquid repellent membrane 30 are simply referred to as “fluorine compound” without distinction.

In the fluorine compounds adjacent to each other on the base fabric 20, the binding moieties 312 bind to each other. More specifically, when the binding moiety 312 is represented by —Z—O—* (formula (i)), the fluorine compounds adjacent to each other on the base fabric 20 have an intermolecular bond formed by mutual binding of Z. Here, Z in the formula (i) is a moiety represented by the reference numeral 311 in FIG. 3, and is an atomic group containing a silicon atom. * represents a binding site to the surface of the base fabric 20. By intermolecular bonding between the fluorine-containing organic compounds constituting the monomolecular membrane in this manner, the liquid repellency and abrasion resistance are improved.

Z (311) is an atomic group containing a Si atom as described above.

According to one example, Z (311) may be an atomic group containing a C atom that binds to an O atom, and a Si atom as shown in FIG. 4. In that case, the fluorine compounds adjacent to each other on the base fabric 20 bind to each other through an intermolecular bond of a —C—Si—C—Si— chain formed by mutual binding of Z (311).

According to another example, Z (311) may be an atomic group containing a Si atom that binds to an O atom, and an O atom as shown in FIG. 5. In that case, the fluorine compounds adjacent to each other on the base fabric 20 bind to each other through an intermolecular bond of a siloxane bond (—O—Si—O—Si— chain) formed by mutual binding of Z (311).

In one aspect, the molecular bond formed between the fluorine compounds constituting the monomolecular membrane is preferably a —C—Si—C—Si— chain.

The terminal perfluoroalkyl group 33 is, for example, a linear perfluoroalkyl group. The number of carbon atoms of the terminal perfluoroalkyl group 33 can be selected within a range of 4 or less (C1 to C4). The terminal perfluoroalkyl group 33 is preferably upright along the perpendicular line direction with respect to the surface of the base fabric 20. When the number of carbon atoms of the terminal perfluoroalkyl group 33 is increased, it becomes easy to make the terminal perfluoroalkyl group 33 upright, but such a terminal perfluoroalkyl group has an adverse effect on a human body such as carcinogenicity.

The spacer linking group 32 links the terminal perfluoroalkyl group 33 to the binding moiety 312. The presence of the spacer linking group 32 is advantageous in that the terminal perfluoroalkyl group 33 has an upright structure along the perpendicular line direction with respect to the surface of the base fabric 20. In one aspect, the terminal perfluoroalkyl group 33 preferably binds to a residual moiety of the fluorine compound through an ether bond. The spacer linking group 32 is, for example, a perfluoropolyether group.

As a raw material of such a liquid repellent membrane 30, for example, a fluorine compound represented by the following general formula (1) or (2) can be used.

In the general formulae (1) and (2), p is a natural number between 1 and 50 and n is a natural number between 1 and 10.

Alternatively, as the raw material of the liquid repellent membrane 30, for example, a fluorine compound in which a moiety to become the binding moiety 312 includes an alkoxysilyl group and a reactive functional group R as represented by the following general formula (3) can also be used.

In the general formula (3), p is a natural number between 1 and 50, n is a natural number between 1 and 10, and R is the above-mentioned reactive functional group.

The film thickness of the liquid repellent membrane 30 is not particularly limited. The film thickness may be, for example, between 10 nm and 100 nm.

The liquid repellent cloth or liquid repellent film 1 shown in FIG. 1 is obtained, for example, as follows.

First, when the base fabric 20 includes almost no functional groups such as a hydroxy group necessary for binding to the fluorine compound on the surface, the base fabric 20 is preferably subjected to a pretreatment as described below prior to the formation of the liquid repellent membrane 30.

For example, one principal face of the base fabric 20 is subjected to an ion plasma treatment in an argon-oxygen mixed gas, thereby modifying the surface. The ion plasma treatment is performed, for example, as follows. That is, the base fabric 20 is placed in a vacuum chamber, and air in the chamber is withdrawn under vacuum. Then, the atmosphere surrounding the base fabric 20 is replaced with an argon-oxygen mixed gas, and thereafter, a plasma is generated.

By performing the ion plasma treatment in an atmosphere containing oxygen, the surface of the base fabric 20 is modified with a hydroxy group, In addition thereto, by performing the ion plasma treatment in an atmosphere containing argon, dirt adhered to the surface of the base fabric 20 is removed.

The ion plasma treatment is preferably performed in an argon-oxygen mixed gas having an oxygen concentration of 50 vol % or less, more preferably performed in an argon-oxygen mixed gas having an oxygen concentration within a range of 20 to 50 vol %. When the oxygen concentration is too high, the surface of the base fabric 20 may be damaged to cause surface roughness. When surface roughness is caused on the base fabric 20, the binding to the liquid repellent membrane 30 may be insufficient.

The ion plasma treatment is preferably performed for 100 seconds or more, more preferably performed for 200 seconds or more. When the plasma irradiation time is too short, the surface modification of the base fabric 20 may not be sufficiently performed.

Subsequently, the fluorine compound is supplied to the surface of the base fabric 20 by a vacuum deposition method. Then, hydrolysis and dehydration condensation are caused, thereby binding the fluorine compound to the surface of the base fabric 20 and also allowing intermolecular bonding of the fluorine compound to occur. In this manner, the liquid repellent cloth or liquid repellent film 1 having the liquid repellent membrane 30 on the base fabric 20 can be formed.

Second Embodiment

The liquid repellent cloth or liquid repellent film 1 can be used for various products required to have liquid repellency. For example, the liquid repellent cloth or liquid repellent film 1 can be favorably used for various fiber products or synthetic resin film products (hereinafter referred to as “plastic products”). In FIG. 2, one example of application of the liquid repellent cloth or liquid repellent film 1 is shown.

FIG. 2 is a schematic view of a partial cross section of an umbrella 10, and the liquid repellent cloth or liquid repellent film 1 is used as a canopy.

The umbrella 10 further includes a shaft 11, a top notch 12, a runner 13, ribs 14, stretchers 15, rib tips 16, a ferrule 17, and a handle (not shown).

The shaft 11 includes a top spring (not shown) for keeping a state where the umbrella 10 is opened in the vicinity of one end thereof. Further, the shaft 11 includes a bottom spring (not shown) for keeping a state where the umbrella 10 is closed in the vicinity of the other end thereof.

The ferrule 17 is attached to an end portion on the top spring side of the shaft 11. The handle is attached to an end portion on the bottom spring side of the shaft 11.

The top notch 12 is fixed to the shaft 11 at a position between the ferrule 17 and the top spring and near the ferrule 17. The top notch 12 supports one end of each rib 14.

At the other end of the rib 14, the rib tip 16 is provided. The rib 14 includes a joint (not shown) at a position at which the distance from the top notch 12 is substantially equal to the length of the stretcher 15.

The runner 13 is supported by the shaft 11 between the handle and the top notch 12. The runner 13 is movable in the length direction of the shaft 11 and can be locked by the bottom spring and the top spring. The runner 13 supports one end of each stretcher 15.

The other end of each stretcher 15 is supported by the joint of the rib 14. The length direction of each stretcher 15 is substantially parallel to the length direction of the shaft 11 in a state where the runner 13 is locked by the bottom spring. When the runner 13 is moved to the position of the top spring from this state, an angle formed by the length direction of the runner 13 with respect to the length direction of shaft becomes larger. As a result, an angle formed by the length direction of the rib 14 with respect to the length direction of shaft also becomes larger.

The liquid repellent cloth or liquid repellent film 1 is supported by the ribs 14 as a canopy. The liquid repellent cloth or liquid repellent film 1 is disposed so that a rear face side 101 becomes the base fabric (not shown) and the front face side 102 becomes the liquid repellent membrane (not shown).

When the base fabric is a fiber cloth, the umbrella 10 is a fabric umbrella including the liquid repellent cloth as the canopy. Further, when the base fabric is a synthetic resin film, the umbrella 10 is a so-called “plastic umbrella” including the liquid repellent film as the canopy.

Further, the liquid repellent cloth or liquid repellent film 1 can be favorably used for various fiber products or plastic products other than an umbrella. Specific examples include a raincoat, rain shoes, a waterproof sheet, a curtain, a table cloth, outdoor wear, sportswear, work clothing, protective clothing, a tent, and a car sheet.

<Effects>

The liquid repellent cloth or liquid repellent film described above has excellent liquid repellency and abrasion resistance, and therefore can be favorably used for a canopy of an umbrella, and also for various fiber products and plastic products. Further, according to the liquid repellent cloth or liquid repellent film described above, problems of environmental load and working environment can be significantly improved.

EXAMPLES

The performance of the liquid repellent membrane described above was confirmed as follows.

EXAMPLE

First, as the base fabric, a polyethylene film was prepared. Subsequently, the base fabric was subjected to a plasma treatment in a reduced pressure atmosphere containing an argon-oxygen mixed gas.

Subsequently, a fluorine compound was supplied onto this film by a vacuum deposition method. Then, hydrolysis and dehydration condensation were caused, thereby binding the fluorine compound to the surface of the film and also allowing intermolecular bonding of the fluorine compound to occur. The fluorine compound used here is represented by the above general formula (1), and is a compound in which p and n are 1 and 10, respectively. In this manner, a liquid repellent film having a liquid repellent membrane on the film was formed.

COMPARATIVE EXAMPLE

First, the same base fabric as used in Example was prepared. Subsequently, the base fabric was subjected to the same plasma treatment as performed in Example. Subsequently, on the base fabric, CYTOP (registered trademark: Type A) manufactured by Asahi Glass Co., Ltd. as the fluorine compound was formed by a coating method. The fluorine compound used here is a compound having a terminal group containing an alkoxysilane group at both terminals of a polymer main chain represented by the following chemical formula (4). Then, hydrolysis and dehydration condensation were caused, thereby binding the fluorine compound to the surface of the base fabric. In this manner, a sample having a liquid repellent membrane on the base fabric was formed.

Test Example 1

The samples of Example and Comparative Example were cut to a width of 15 mm. Each of these samples was dipped in an inkjet ink for several seconds in such a manner that the principal face thereof was parallel to the gravity direction. Then, only a portion with a length of 45 mm of each sample was pulled up from the ink, and a time required for the ink to disappear from the pulled up portion was measured. As a result, the ink disappeared from the pulled up portion immediately after the portion was pulled up from the ink in both samples.

Test Example 2

The same samples as described above were prepared, and the surfaces of these samples were rubbed back and forth 10000 times with a rubber plate. Each sample after being rubbed was dipped in an inkjet ink for several seconds in such a manner that the principal face thereof was parallel to the gravity direction. Then, only a portion with a length of 45 mm of each sample was pulled up from the ink, and a time required for the ink to disappear from the pulled up portion was measured.

As a result, in the sample of Example, the ink disappeared from the pulled up portion immediately after the portion was pulled up from the ink. On the other hand, in the sample of Comparative Example, the ink did not disappear from the portion pulled up from the ink. The reason why the decrease in liquid repellency occurred in the sample of Comparative Example in this manner is considered that the conformation of the fluorine compound was changed by rubbing, and a group that largely contributes to the liquid repellency was reduced on the surface of the liquid repellent membrane.

From the results of the above Test Examples 1 and 2, it is found that the present embodiment has excellent liquid repellency and abrasion resistance.

The invention is not limited to the embodiments described above and can be modified variously without departing from the gist of the invention at an implementation stage. Also, the respective embodiments may be appropriately combined and carried out, and combined effects can be obtained in that case. Further, the embodiments described above include various inventions, and various inventions can be extracted by combinations selected from a plurality of disclosed constituent elements. For example, even if several constituent elements are deleted from all the constituent elements described in the embodiments, a configuration in which the constituent elements are deleted can be extracted as the invention when the problem can be solved and the effect can be obtained. 

What is claimed is:
 1. A liquid repellent cloth or liquid repellent film comprising: a base fabric selected from a fiber cloth or a synthetic resin film; and a liquid repellent membrane supported on at least one principal face of the base fabric, wherein the liquid repellent membrane is a monomolecular membrane of a fluorine-containing organic compound that binds to a surface of the base fabric through a binding moiety represented by —Z—O—* (wherein Z represents an atomic group comprising a Si atom, and * represents a binding site to the surface of the base fabric) and includes a perfluoroalkyl group having 4 or less carbon atoms at a terminal, and the fluorine-containing organic compound undergoes intermolecular bonding between the fluorine-containing organic compounds adjacent to each other by mutual binding of Z in the formula.
 2. The cloth or film according to claim 1, wherein Z in the formula is an atomic group comprising the Si atom and a C atom that binds to the O atom in the formula, and the intermolecular bond formed by mutual binding of the Z is a —C—Si—C—Si— chain or Z in the formula is an atomic group comprising an O atom and the Si atom that binds to the O atom in the formula, and the intermolecular bond formed by mutual binding of the Z is a —Si—O—Si—O— chain.
 3. The cloth or film according to claim 1, wherein the perfluoroalkyl group binds to a residual moiety of the fluorine-containing organic compound through an ether bond.
 4. The cloth or film according to claim 1, wherein the base fabric is a fiber cloth comprising a synthetic fiber, a semi-synthetic fiber, a regenerated fiber, and/or a natural fiber.
 5. The cloth or film according to claim 1, wherein the base fabric is a synthetic resin film comprising a polyester-based film, a polyamide-based film, and/or a polyolefin-based film.
 6. The cloth or film according to claim 1, wherein the base fabric is a synthetic resin film comprising an ethylene-vinyl alcohol copolymer resin (EVOH) or an ethylene-vinyl acetate copolymer resin (EVA).
 7. The cloth or film according to claim 1, wherein the base fabric is a synthetic resin film having a thickness of from 50 μm to 200 μm.
 8. The cloth or film according to claim 1, wherein the liquid repellent membrane is a film having a thickness of from 10 nm to 100 nm.
 9. The cloth or film according to claim 1, wherein the base fabric has a surface that is modified to comprise hydroxy groups by ion plasma treatment.
 10. An umbrella, comprising the liquid repellent cloth or liquid repellent film according to claim
 1. 11. A product, comprising the liquid repellent cloth or liquid repellent film according to claim
 1. 